In-situ synthesis of interconnected SWCNT/OMC framework on silicon nanoparticles for high performance lithium-ion batteries

In spite of silicon has a superior theoretical capacity, the large volume expansion of Si anodes during Li^+ insertion/extraction is the bottle neck that results in fast capacity fading and poor cycling performance. In this paper, we report a silicon, single-walled carbon nanotube, and ordered mesoporous carbon nanocomposite synthesized by an evaporation-induced self-assembly process, in which silicon nanoparticles and single-walled carbon nanotubes were added into the phenolic resol with F-127 for co-condensation. The ordered mesoporous carbon matrix and single-walled carbon nanotubes network could effectively accommodate the volume change of silicon nanoparticles, and the ordered mesoporous structure could also provide efficient channels for the fast transport of Li-ions. As a consequence, this hybrid material exhibits a reversible capacity of 861 mAh g^(-1) after 150 cycles at a current density of 400 mAg^(-1). It achieves significant improvement in the electrochemical performance when compared with the raw materials and Si nanoparticle anodes.

Size effect of Si particles on the electrochemical performances of Si/C composite anodes

A series of Si/C composites were fabricated based on pitch and Si powders with particle sizes of 30, 100, 500, and 3000 nm. The size effects of the Si particles in the Si/C composites were investigated for lithium-ion battery anodes. The nanoscale Si and Si/C composites exhibited good capacity retentions. Scanning electron microscopy showed that exterior and interior cracks emerging owing to volume expansion as well as parasitic reactions with the electrolyte could well explain the performance failure.

Recent advances in two-dimensional nanomaterials-based electrochemical sensors for environmental analysis

With the rapidly increased concerns in environmental pollution, there have been urgent needs to develop fast, sensitive, low-cost and multiplexed sensing devices for the detection of environmental pollutants. Two-dimensional(2D) nanomaterials hold great promise due to their unique chemical and physical properties, which have been extensively employed to monitor the environmental pollutants combined with different detection techniques. In this review, we summarize recent advances in 2D nanomaterials-based electrochemical sensors for detecting heavy metal ions, organic compounds, pesticides, antibiotics and bacteria. We also discuss perspectives and challenges of 2D nanomaterials in environmental monitoring.

Research progress on the design of electrolyte additives and their functions for zinc-ion batteries

In recent years,zinc-ion batteries(ZIBs)have been considered one of the most promising candidates for next-generation electrochemical energy storage systems due to their advantages of high safety,high specific capacity and high economic efficiency.As an indispensable component,the electrolyte has the function of connecting the cathode and the anode,and plays a key role in the performance of the battery.Different types of electrolytes have different effects on the performance of ZIBs,and the use of additives has further developed the research on modified electrolytes,thus effectively solving many serious problems faced by ZIBs.Therefore,to further explore the improvement of ZIBs by electrolyte engineering,it is necessary to summarize the current status of the design of various electrolyte additives,as well as their functions and mechanism in ZIBs.This paper analyzes the challenges faced by different electrolytes,reviews the different solutions of additives to solve battery problems in liquid electrolytes and solid electrolytes,and finally makes suggestions for the development of modified ZIB electrolytes.It is hoped that the review and strategies proposed in this paper will facilitate development of new electrolyte additives for ZIBs.

含LiDFOB的FEC/PC/DMC基电解液的高电压电化学性能

利用氟代碳酸乙烯酯（FEC）和二氟草酸硼酸锂（LiDFOB）优良的成膜性、稳定性和耐高压性,研究了在1 mol/L LiPF6FEC/碳酸丙烯酯（PC）/碳酸二甲酯（DMC）中加入LiDFOB和三（三甲基硅烷）硼酸酯（TMSB）对高电压材料LiNi（0.5）Mn（1.5）O4电化学性能的影响,利用循环伏安法和扫描电镜分析了两种电解液中电化学性能的差异.结果表明,在FEC基电解液中加入LiDFOB和添加剂TMSB使电解液的分解电位提高至5.5 V（vs.Li/Li^＋）以上,对铝箔有良好的钝化作用.Li/LiNi（0.5）Mn（1.5）O4半电池在含LiDFOB和TMSB的电解液中的初始放电比容量达126.8 mA·h/g,库伦效率为99%,充放电200次后比容量仍为108.2 mA·h/g,容量保持率为85.3%.而在不含LiDFOB和TMSB的电解液中,电池容量迅速衰减,85次充放电循环后容量保持率仅为60.7%.

Defects in Graphene:Generation,Healing,and Their Effects on the Properties of Graphene:A Review

Graphene has attracted immense investigation since its discovery.Lattice imperfections are introduced into graphene unavoidably during graphene growth or processing.These structural defects are known to significantly affect electronic and chemical properties of graphene.A comprehensive understanding of graphene defect is thus of critical importance.Here we review the major progresses made in defectrelated engineering of graphene.Firstly,we give a brief introduction on the types of defects in graphene.Secondly,the generation and healing of the graphene defects are summarized.Then,the effects of defects on the chemical,electronic,magnetic,and mechanical properties of graphene are discussed.Finally,we address the associated challenges and prospects on the future study of defects in graphene and other nanocarbon materials.

Chalcogenides metal-based heterostructure anode materials toward Na^(+)-storage application

Sodium-ion batteries(SIBs)are promising candidates for future large-scale energy storage systems due to their low cost and high safety.However,the sluggish kinetics caused by the large radius of Na+impedes the practical application of SIBs.Heterostructure engineering has emerged as an attractive strategy to alleviate this critical issue due to its intriguing contributions to accelerating electrons/ions transfer kinetics,improving structural stability,and enhancing Na^(+)adsorption ability.From this perspective,in this review,we introduce the vital role of heterostructure on the performance of SIBs firstly.The commonly used approaches for synthesizing chalcogenides metal-based heterostructure anodes are then presented.Subsequently,we discuss the recent progress of various chalcogenides metal-based anodes in detail.Finally,we provide a concluding discussion on the current challenges and perspectives of future development of the heterostructure anode materials for high-performance SIBs.

Novel ionic liquid based electrolyte for double layer capacitors with enhanced high potential stability

Developing electrolyte with high electrochemical stability is the most effective way to improve the energy density of double layer capacitors(DLCs), and ionic liquid is a promising choice. Herein, a novel ionic liquid based high potential electrolyte with a stabilizer, succinonitrile, was proposed to improve the high potential stability of the DLC. The electrolyte with 7.5 wt% succinonitrile added has a high ionic conductivity of 41.1 m S cm^(-1) under ambient temperature, and the DLC adopting this electrolyte could be charged to 3.0 V with stable cycle ability even under a discharge current density of 6 A g^(-1). Moreover, the energy density could be increased by 23.4% when the DLC was charged to 3.0 V compared to that charged to 2.7 V.

Three new bifunctional additive for safer nickel-cobalt-aluminum based lithium ion batteries

Three different types of new electrolyte additives were adopted as flame retardant to improve the safety of nickel-cobalt-aluminum(LiNi_(0.8)Co_(0.15)Al_(0.05)O_2, abbreviation NCA) based lithium batteries. By adding 5 wt% of the additives, an obvious flame retardant effect can be observed for the electrolyte. Furthermore,it was found that the additives can help for forming a stable cathode electrolyte interface(CEI) film on the NCA cathode, which are important for enhancing the thermal stability of the electrolyte and make the electrolyte obviously reduce the flammability, as well as good effect on the cycling cycle performance of the battery. These results indicate that our flame retardant are favorable additives in conventional liquid electrolytes for rechargeable lithium-ion batteries with good safety and high performances.

Revealing Quasi-1D Volume Expansion in Na-/K-Ion Battery Anodes:A Case Study of Sb_(2)O_(3)Microbelts

Tailoring a rational structure to control the huge volume variation is practical in regulating alkali-ion battery performance on the basis of the anisotropic properties of crystallized anode materials.Here,a double-serrated orthorhombic antimony oxide(Sb_(2)O_(3))microbelt was prepared by a thermally induced recrystallization/sublimation process.In situ transmission electron microscopy(TEM),in situ X-ray powder diffraction(XRD),and ex situ scanning electron microscopy(SEM)measurements demonstrate that Sb_(2)O_(3)microbelts exhibit a quasi-one-dimensional expansion perpendicular to the belt(along the[100]direction)during sodiation.The unconstrained microbelt surface space can appropriately accommodate the oriented volume variation.Thus,Sb_(2)O_(3)microbelts exhibit enhanced cycling and rate performance in half-cell sodium-ion batteries samples.Via support of reduced graphene oxide(RGO),Sb_(2)O_(3)@RGOcomposites deliver good rate capability(312.3 mAh g−1 at 3 A g−1)for sodium-ion full-cell batteries and good cycling performance(473.9 mAh g−1 at 100 mA g−1 after 100 cycles)for half-cell potassium-ion batteries.In situ Raman measurements reveal that the conversion/alloying-type Sb_(2)O_(3)anode undergoes a fully reversible alloying reaction and partially reversible conversion mechanism,which explains its irreversible capacity during the first cycle.The delicate structural design and clarification of the alkali-ion storage mechanisms facilitate the development of Sb_(2)O_(3)anodes for energy storage applications.

Ternary nanoarray electrode with corn-inspired hierarchical design for synergistic lithium storage

Single-component anode materials can barely satisfy the growing demand for next-generation Li-ion batteries with higher capacity and cyclability. Thus developing multi-component synergistic electrodes has become a critical issue. Herein, inspired by natural corn, a ternary hierarchical self-supported array design is proposed. Based on a sequential transformation route, Si/C-modified C0304 nanowire arrays are constructed on 3D Ni foams to form a binder-free integrated electrode. Specifically, an ionic liquid-assisted electrodeposition strategy is employed to prepare discrete ultrafine Si nanoparticles on nanoscale array substrates, which follow the Volmer-Weber island growth mode. In this corn-mimetic system, kernel-like Si nanoparticles and a husk-like carbon coating layer function as enhancing and protecting units, respectively, to improve the capacity and stability of the cobalt oxide basic unit. Taking advantage of a synergistic effect, the ternary nanoarray anode achieves a significant performance enhancement compared to pristine Co304, showing a special capacity as high as -1,000 mAh·g^-1 at 100 mA·g^-1. By extending this corn-mimetic hierarchical array design to other basic, enhancing, and protecting units, new ideas for constructing synergistic nano-architectures for energy conversion and storage field are developed.